Crankcase oil purifier



July 10, 1945. H. H. CANNON 2,379,364

CRANKCAS E OIL PURIFIER Filed-April 7, 1942 l9 H.H. CANNON /47 I VENTQRATTORNEY,

Patented July 10, 1%45 2,379,864 D @RANKCASE om rrmminit Hugh. HarleyCannon, Lcs Angeles, Calif. Application April 7, 1942, Serial No.438,046

2 (Claims.

The invention pertains to the class of oil purifiers which are attachedto and operated by an internal combustion engine and which continuouslyfilter a stream of oil drawn from the crankcase and returned thereto.

The type of purifier now in common use is arranged on the discharge of apressure pump, usually the pump which supplies forced feed to theengine. The filtering element operates with a relatively highsuperatmospheric pressure on its intake side and discharges into thecrankcase at atmospheric pressure.

I depart from this conventional practice in supplying the filter withoil under substantially atmospheric pressure and in maintaining thedischarge side of the filter under a fluctuating subatmosphericpressure, to-wit, the pressure exist,-. ing momentarily in .the intakemanifold of the engine.

In this departure from conventional practice I realize two notableadvantages: the first in a more efiicient use of the filtering elementfor the removal of suspended solids from the circulated oil than isrealized in operation at higher pressures; the second in removing fromthe oil at least a part and sometimes all of the water and gasoline endswhich tend to accumulate in thecrankcase and depreciate the quality ofthe oil. This latter function is not performed in even a slight degreeby the conventional pressure filtration systems.

A discussion of these advantages and the rationale thereof will be foundfollowing the de- (Cl. 21ll164) scription of a preferred form ofapparatus illustrated in the attached drawing, in which Fig. 1 is avertical section through the assembly, certain interior parts beingshown in ele vation;

Fig, 2 is a detail cross section through the diversion valve 26 of Fig.1, and

Fig. 3 is a fragmental view of a portion of the filtering element 24 andits two layers of covering material. Referring to the drawing, threecylindrical shells Ni, ii, and 62 are separated by diaphragms l3 and I lto form three chambers l5, l6, and ll. These shells and the upper andlower heads 58, and it are of such form and thickness as to withstand anexternally applied pressure of at least 15 pounds per square inch. Thethree sections are removably and nonleakablyjoined in any convenientmanner, as by clamps or small bolts not shown.

The upper or filtering chamber 65 is provided with an inlet connection28 extending to some convenient point in the lower side of the enginecrankcase, to bring, a supply of oil to the filter. This chamber is alsoprovided with a filtering element 2! of sheet metal, perforated withmany small holes 22. The perforate element may be covered with cottoncloth or fine wire gauze as indicated at'it in Fig. 3. It is desirableto interpose between the cloth and the perforate metal a layer 24 ofcoarse mesh wire screen to facilitate the movement into the perforationsof oil which has passed through the cloth. Alternatively the supportingelement 2i may be formed of still and heavy wire mesh screen on whichthe filter cloth may be mounted directly. In either case the cloth sackis tied firmly around the neck at the lower end of the element. I

The filtered oil passing into the interior of element 2! gravitates intothe float chamber is through openings 25 in diaphragm it. The fioatchamber is provided with a diversion valve 26 which may conveniently becarried on two tubes 2i and 28 sealed into the walls of shell M. Thefirst of these tubes extends to the engine intake manifold, connectinginto it at any convenient point between the throttle valve and theengine; the second communicates with the atmosphere outside the chamber.

Referring now to Fig. 2, the body of the valve has ports communicatingwith tubes 21 and 28 and two additional ports 29 and 30, bothcommunicating with the interior of the fioat chamber. Within the valvebody is fitted a rotatable plug 3! having internal channels 32 and 33.These channels are arranged to place tube 21 in communication with port29 in the position of the plug shown in Fig. 2, and to place tube 28 incommunication with port (iii in another position (that indicated in Fig,1). The movement of the plug between these two positions is effected byan arm 34 the movement of which is limited by stops 35 and 36. This armis provided with a tension spring 37 which completes its travel afterpassing over dead center.

Referring again to Fig. 1, the float chamber is provided .with a float38 guided by a fioat rod 39 which is longitudinally movable in a guideill attached to diaphragm It and in a perforation in diaphragm it. Thefloat rod is provided with two pairs of collars, il-t2 and iti l, thefirst pair engaging the end of arm 35 to actuate the valve, the secondpair engaging the float to actuate the float rod.

As the float chamber fills with oil drainin down through openings 25,the float rises-until it engages collar 43, thus lifting the rod andrelatively low 2 causing collar 42 to engage the lower side of arm 34and to move the arm past its dead center, from which point the travel iscompleted by the tension of spring 31. This movement of the arm bringsthe plug 3| into the position in which port 33 places tube 28 and port30 in communication while communication between tube 21 and port 29 isinterrupted. Atmospheric air then enters through tube 28, breaking thevacuum and momentarily terminating filtration. The oil contained in thefloat chamber thereupon gravitates through a neck 45 attached todiaphragm l4, lifts the clapper valve 46 and flows through drain pipel'l back to any convenient point in the engine crankcase.

-When the oil level in the float chamber has subsided to the point atwhich float 38 engages collar 44 the reverse of the above movementstakes place. Float rod 39 is urged downwardly, collar ll engages the topof arm 34 and carries it over the center, spring 31 completes the travelof the arm and brings plug 3| to the position shown in Fig. 2. The entryof external air to the float chamber is thus shut oil! and the enginemanifold placed in communication with the interior of the float .chamberand, through openings '25, with the interior of filtering element 2|.Filtration then begins and the float chamber starts to fill withfiltered oil, thus completing the cycle.

The apparatus exemplified in the above description has two functions: tofilter the oil and thus remove suspended solids, and to evaporate fromthe'oil entrained water ,and dissolved gasoline.

The pressure drop across the filter is equal to the difference betweenatmospheric pressure and the momentary pressure in the intake manifold.In engines of the automotive type the intake pressure varies betweeninches and inches of mercury below atmosphere, or with atmosgphericpressure at normal of 14.7 pounds, from 13 pounds to 3 pounds per squareinch absolute. v

-During the greater part of the time of operation of an automotivevehicle the manifold pressure is close to the lower end of the range, orfrom 3 pounds to 5 pounds absolute. At intervals corresponding to theperiodicity of float operation I the pressure drop across the filterfalls to zero.

This fluctuation in filtering pressure, and the effective filteringpressure, have a highly beneficial effect on the useful life of thefiltering element. The application of the high and constant pressureincident to'the use of the conventional apparatus results in a verylarge flow through a fresh filtering element and in the rapid formationof a dense and impenetrable filter cake. As no flow rate larger thanthat required to keep the oil clean is useful, the too rapid choking ofthe filter has no compensating advantage. When subatmospheric filteringpressures are used, the initial flow rate is materially less but thecake formed is'more open and permeable and the useful lifeof the filteris thus largely extended. Fur her, the working of the slightly resilientfilte .element which follows from fluctuation in pressure tends to moveslimy colloids through the filter and thus maintain it in permeablecondition. In brief, the eflect of the reduced average pressure coupledwith repeated pressure fluctuation is to cause the filtering element todeliver a reduced quantity of filtered oil, per unit of surface area,over a much extended period.

On emerging from the inner. or discharge side of the filtering elementthe filtered oil is spread such in the of reduced pressures atrelatively high temperaisting in the engine intake during its passagedown the inner wall of the filter and on the upper surface of the poolcollecting in the float chamber. The amount of evaporation of water andof gasoline ends thus produced is a function of the temperature of theoil and of the vapor pressure of each liquid over the pressure rangeexisting in the float chamber and the filtering element. Under mostcircumstances the water contained in the oil will actually boil and becompletely vaporized; thus the normal operating temperature of theautomotive crankcase ranges from to 200 Fahr. and the oil enters thefiltering chamber at substantially the same temperature unless it beheated to a higher temp ture deliberately. At 3 pounds absolute theboiling point of water is 141 and at 13 pounds absolute is 205 Fahr., sothat even at 150 crankcase temperature the water would be graduallysweated out. Of course it isnot necessary that the oil should becompletely dried in one passage through the apparatus, as it isrepeatedly circulated.

to accumulate and which are not driven out of the crankcase atatmospheric pressure have considerably higher boiling points, but at anyreduced pressure they have a positive vapor pressure by which they aresweated out more or less rapidly as the inlet manifold pressurefluctuates. Thus, while it is unlikely that at any time the oil will becompletely stripped of gasoline ends, the quantity existing in the oilbody is held to a constant, the magnitude of which will vary with thecrankcase temperature (or the temperature to which the oil is heated)and the minimum manifold pressure in each specific engine as that engineis operated. In any case the maximum quantity of gasoline'ends possibleto accumulate in the oil is below the proportion which, can causeserious dilution of the oil. When engine is idling, as at tramcintersections, manifold pressure is near minimum absolute.

Besides removing the water which exists as circulated oil stream, theapplication ture has the effect of dehydrating the slimy col loids(mainly heavy metal soaps) and thus coagulating them. In the-dehydratedform they are amenable to filtration and thus are removed on the nextpassage through the filter, whereas in their hydrated form they passthrough the filter or choke it rapidly if they do not. so pass.

In the application of the above descrlbed principle to engines operatingat relatively low crankcase temperatures, or to engines operating atconstant load with inches below atmosphere, it is desirable and may benecessary to heat the oil to a higher temperature, ordinarily somewhatabove the boiling point of water, to ensure the desired stripping out ofthe gasoline ends. Heat may be applied to the oil stream during itspassage from the crankcase to the filtering chamber, and exhaust heatmay be used for that purpose. If the heat thus imparted is objectionablein the crankcase the stream draining down from the float chamber may becooled in its return passage.

I claim as my invention:

1. Apparatus for purifying oil drawn from the an intake pressure only afew.

- as'a'asea unimpeded communication between the interir of saidfiltering element and said medial chamher; a reciprocable valve withinsaid medial chamber, said valve having ports communicating with theinterior of said chamber: channels connecting said valve respectivelywith the outside atmosphere and with the intake manifold of said engine;es within said valve arranged to place said channels alternately incommunication with said ports when said valve is reciprocated; a fioatwithin said medial chamber operatively connected with said valve toreciprocate. the same and thereby to open said atmosphere channel andclose said manifold channel as said medial chamber fills with filteredoil and to reverse said movements when said medial chamber empties; achannel aii'ording communication between saidmedial chamber and saidlower chamber and a gravity operated check valve arranged to permitdownward flow and prevent upward flow of fluids through last saidchannel, and a channel afl'ording communication between said lowerchamber and said crankcase.

2. Apparatus for purifying oil drawn from the crankcase of an internalcombustion engine, comprising: a vertically arranged casing divided intothree chambers by horizontally disposed, spaced partitions; a verticallyarranged, hollow filtering element in the uppermost of said chambers'and means for delivering oil from said crankcase onto said element toflow over the vertical surfaces thereof; a port in the upper of saidpartitions affording constant and unimpeded communication between theinterior of said filtering element and the medial of said chambers;independent channels passing through the wall chamber and communicatingrespectively with the atmosphere and with the intake manifold of saidengine and float actuated valve means within said medial chamber,connected with said independent channels and adapted to place saidchannels alternately in communication with said medial chamber; achannel aifording communication between said medial chamber and thelowermost of said chambers; a check valve in last said channel arrangedto permit only downward fiow of .liquid therethrough, and a channelconnecting said lowermost chamber with said crank- HUGH HARLEY CANNON.

of said medial

